The invention relates to a sealing bung for bottle closures.
A glass bottle is often closed by means of a metal closure, rolled on the threaded end of the glass finish itself, and a bung composed of elastic substance, usually plastic, that must guarantee the seal of the closure against liquid or gaseous leakage.
If the bottle will contain a liquid which is to be subjected to pasteurization, there is the possibility that, during this treatment and because of the high temperatures involved, the plastic bung will lose its elasticity and soften, thus causing loss of the seal on the bottle.
This danger also exists in the presence of high pressures or the development thereof.
Loss of seal has been typically prevented by thickening the bung's walls, however, causes great difficulties during the insertion of the bung itself into the bottle.